As is described, for example, in the under-mentioned patent citation 1 which corresponds to an application filed by the same applicant as the present application, as one of friction brake devices, a friction brake device has been known which has a pair of friction members that are pressed against two sections of a brake rotor. In particular, in the brake device described in the above-mentioned patent citation 1, the friction members are pressed against the side surface of a disk part of the brake rotor and against the inner surface of a cylindrical part provided on the outer peripheral portion of the brake rotor.
In this type of brake device, a braking torque is generated by means of both friction engagement by the revolution of the friction members around the rotation axis relative to the disk part of the brake rotor and friction engagement by rotation of the friction members with the inner surface of the cylindrical part of the brake rotor. Accordingly, as compared to a brake device where the friction members are pressed only against the side surface of the disk part of the brake rotor, a higher braking torque can be generated.